When you say “God”, it appears that you already have an image of God in your mind. You asked probably to confirm that your image or idol is anything more than fiction. But no amount of confirmation can lead you to the truth, for almost everyone you ask would have his own idol.
The very construction of the sentence is perverted. The use of “a” already tells me that you think God is both countable and a noun. It already frames you to look for an object. If you think that God is omnipresent, tell me how it is possible for a countable noun to be omnipresent. Only uncountable nouns can be omnipresent, such as cosmic microwave radiations.
Consider what happens when you go to a furniture shop to purchase a chair. By saying the word “chair”, you posit a definition that the seller must know. Similarly, when you say “God”, you have already conceptualized God. Now, when you look for God, you chase a concept that you yourself have posited, which is nothing but your imagination. If you don’t find it, you may become an atheist. No, you may think that you have become atheist when all you have done is abandoned your idols of God. Some philosophers worry about the rise of atheism when it is not a problem at all. A great change in human consciousness is coming. People’s becoming atheists is only a part of it. They are simply moving away from idol worship and religion, both of which need to go. For you to find out anything, you must first get rid of everything that it is not.
I see the same when people ask about life, purpose, meaning, etc. All of these are perverted questions. When a man says “what is life”, he, by using the term, posits a definition of life. It is that which he means by “life”. He first creates an illusion. Then, he wants to get out of it. The simplest way for him to escape his illusions is to give up his knowledge. Once he no longer knows “life” and its definition, he won’t ask that question. His knowledge was just as illusionary as the knower (himself) anyway.
If you seek wisdom, you must first give up everything you know. Give up even your desire to know. If you are looking for God, let go of all knowledge of it. Let even the word “God” be dissolved into nothingness. Once you are free of all concepts and forms, you will be able to see that you could not see before because your frame was putting everything into forms and concepts. When a mathematician sees two sets of parallel lines, his frame (knowledge) makes him see a parallelogram. Is it really a parallelogram? Ask a baby who does not know math. Did he laugh? Was it a joke?
Update on Oct 8, 2020 -
I have another spin on this. Asking if there is a God assumes that you know what you are looking for. If you didn't, you wouldn't say "a God". The problem is you may find what you are looking for and live forever in a delusion. Consider an analogy. A man goes to a furniture shop to look for a chair. He thinks chair is a four-legged piece of furniture that you can sit on. He finds something four-legged, which matches his idea of a chair, and takes it home. Now, he lives comfortably in the delusion that he has a chair. He has found what he was looking for, but it is not a chair. Therefore, before you look for a chair, before you even say chair, you must know chair. If you knew God before you called that what you knew God, you would have never asked the question.